130 citations · 964 across the 49 of their papers we have counts for
41 papers · 1 filter
Interesting radiative patterns of neutrino mass in an SU(3)_C X SU(3)_L X U(1)_X model with right-handed neutrinos
Darwin Chang, Hoang Ngoc Long
We investigate a simple model of neutrino mass based on SU(3)_C X SU(3)_L X U(1)_X gauge unification. The Yukawa coupling of the model has automatic lepton-number symmetry which is…
Generalized Study with Isospin-phased Topological Approach on the Puzzle
D. Chang, C. S. Chen, H. Hatanaka +1
We study the decay processes by using generalized decay amplitudes with both the final state re-scattering strong phases and the topological quark diagrammatic strong p…
Electric Dipole Moment in the Split Supersymmetry Models
Darwin Chang, We-Fu Chang, Wai-Yee Keung
We study an important contribution to the electric dipole moment (EDM) of the electron (or quarks) at the two-loop level due to the -EDM in the recently proposed scenario of spl…
Perturbative SO(10) Grand Unification
Darwin Chang, Takeshi Fukuyama, Yong-Yeon Keum +2
We consider a phenomenologically viable SO(10) grand unification model of the unification scale around GeV which reproduces the MSSM at low energy and allows pertu…
A model of CP Violation from Extra Dimension
Darwin Chang, Chian-Shu Chen, Chung-Hsien Chou +1
We construct a realistic model of CP violation in which CP is broken in the process of dimensional reduction and orbifold compactification from a five dimensional theories with $SU…
Natural Kobayashi-Maskawa Model of CP Violation and Flavor Physics
Darwin Chang, Wai-Yee Keung
We explore the possible tie between the naturalness of having a very small strong CP parameter in the Kobayashi-Maskawa Model and the flavor symmetry. We provide many examples…
A New Class of Solutions to the Strong CP Problem with a Small Two-Loop theta
Darwin Chang, Wai-Yee Keung
We present a new class of models which produce zero theta (QCD} angle at the tree and one-loop level due to hermiticity of sub-blocks in the extended quark mass matrices. The struc…
Nambu-Goldstone Bosons in CP Violating theory with Majorana Masses
Darwin Chang, Wai-Yee Keung, Chen-Pin Yeh
We derive some properties of the Nambu-Goldstone boson coupling in theories that have CP violation and Majorana masses. We show explicitly that its diagonal coupling to a Majorana…
New constraint from Electric Dipole Moments on chargino baryogenesis in MSSM
Darwin Chang, We-Fu Chang, Wai-Yee Keung
A commonly accepted mechanism of generating baryon asymmetry in the minimal supersymmetric standard model (MSSM) depends on the CP violating relative phase between the gaugino mass…
Squark Mixing Contributions to CP violating phase gamma
Darwin Chang, We-Fu Chang, Wai-Yee Keung +2
We investigate the possibility that the CP violation due to the soft supersymmetry breaking terms in squark mixing can give significant contributions to the various related par…
Models for Geometric CP Violation with Extra Dimensions
Darwin Chang, Wai-Yee Keung, Rabindra N. Mohapatra
In a recent paper, two of us (D.C. and R.N.M.) proposed a new way to break CP symmetry geometrically using orbifold projections. The mechanism can be realized in the five dimension…
CP asymmetry in the Higgs decay into the top pair due to the stop mixing
Fred Browning, Darwin Chang, Wai-Yee Keung
We investigate a potentially large CP violating asymmetry in the decay of a neutral scalar or pseudoscalar Higgs boson into the top-anti-top pair. The source of the CP nonconservat…
Challenges in Hyperon Decays
Darwin Chang
We give an personal overview of some of the unsolved problems related to hyperon decays. We cover nonleptonic decays, radiative decays and magnetic moments. Some of the theoretical…
Large Two-Loop Contributions to g-2 from a Generic Pseudoscalar Boson
Darwin Chang, We-Fu Chang, Chung-Hsien Chou +1
We calculate the dominant contributions to the muon at the two-loop level due to a generic pseudoscalar boson that may exist in any exotic Higgs sector in most extensions of…
Large CP violation in radiative B decays in supersymmetry without R-parity
Gautam Bhattacharyya, Darwin Chang, Chung-Hsien Chou +1
We demonstrate that the R-parity breaking interactions within their current experimental upper bounds can give rise to large mixing-induced CP asymmetry in exclusive radiative B de…
The Neutron Electric Dipole Moment and CP-violating Couplings in the Supersymmetric Standard Model without R-parity
Darwin Chang, We-Fu Chang, Mariana Frank +1
We analyze the neutron electric dipole moment (EDM) in the Minimal Supersymmetric Model with explicit R-parity violating terms. The leading contribution to the EDM occurs at the 2-…
Radiatively Induced Neutrino Majorana Masses and Oscillation
Darwin Chang, A. Zee
We review and remark on models of radiatively induced neutrino Majorana masses and oscillations. It is pointed out that while the models are capable of accounting for the observed…
Pseudo-Dirac Neutrinos
Darwin Chang, Otto C. W. Kong
We propose a scheme in which a pseudo-Dirac structure for three family of light neutrinos is generated naturally. An extended Higgs sector with a majoron is used for the generation…
Additional two-loop contributions to electric dipole moments in supersymmetric theories
Darwin Chang, We-Fu Chang, Wai-Yee Keung
We calculate the two-loop contributions to the electric dipole moments of the electron and the neutron mediated by charged Higgs in a generic supersymmetric theories. The new contr…
Fitting Precision Electroweak Data with Exotic Heavy Quarks
Darwin Chang, We-Fu Chang, Ernest Ma
The 1999 precision electroweak data from LEP and SLC persist in showing some slight discrepancies from the assumed standard model, mostly regarding and quarks. We show how…
Ruling out the Weinberg Model of Spontaneous CP Violation
Darwin Chang, Xiao-Gang He, Bruce H. J. McKellar
There have been many declarations of the death of the Weinberg model of spontaneous CP violation. Previous studies, before the recent measurements of , indicated that the mod…
On A New Class of Models for Soft CP Violation
David Bowser-Chao, Darwin Chang, Wai-Yee Keung
We elaborate on a new class of models proposed recently by us and compare with another class proposed by Georgi and Glashow(GG). The models can be roughly classified as the righted…
Vector Quark Model and B to X_s gamma Decay
Chia-Hung V. Chang, Darwin Chang, Wai-Yee Keung
We study the meson radiative decay in the vector quark model. Deviation from the Standard Model arises from the non-unitarity of the charged current KM matrix and…
Alternative Interpretation of the Tevatron Top Events
Darwin Chang, We-Fu Chang, Ernest Ma
We propose an alternative interpretation of the top events discovered at the Tevatron in 1995. Given that the charge of the quark jet cannot be measured for the whole sample wi…